Q. 125.0( 2 Votes )
A topper wire of cross-sectional area 0.01 cm is under tension of 20 N. Find the decrease in the cross-sectional area Young modulus of copper = 1.1 × 1011 N m-2 and Poisson ratio = 0.32.

Answer :
1.164 × 10-6 cm2
Given, cross-sectional area,
Tension in the wire,
Young modulus of the wire,
We know, stress,
And strain is given by ,
Young’s modulus then becomes,
therefore, longitudinal strain becomes,
Let the circular cross-section be of diameter
Given, Poisson’s ratio
hence, lateral strain
We know, area is given by
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